1. Field of the Invention
The present invention relates to a clutch mechanism for a power transmission system, which is provided with one drive member, two driven members, and clutch members for effecting connection and disconnection between the drive and driven members. More particularly, the invention relates to a clutch mechanism for a power transmission system, which is suitable for use as the differential locking mechanism of a vehicle.
2. Description of Relevant Art
Various types of systems or devices requiring a clutch mechanism are required to have a special clutch action. For example, one such system or device is equipped with one drive member and two driven members which are rotationally driven by the drive member. Such a system or device can transmit power to the two driven members with both forward and backward rotation of the drive member, so that the clutch thereof functions as a two-way clutch. Moreover, if additional power such as an external force is exerted upon one of the driven members, such driven member can be operatively disassociated from the drive member, while the other driven member remains locked and connected with the drive member, so that the former driven member is permitted to freely rotate at a higher speed than the drive member.
A typical exemplary application wherein a clutch mechanism providing the above-described special clutch action is employed is in a three- or four-wheeled vehicle or the like which is provided with two drive wheels. In such a vehicle, a propeller shaft (i.e., the drive member) which is rotationally driven by the power of a prime mover or an engine, is connected with two axle shafts (i.e., the driven members), which are connected to respective drive wheels, when the propeller shaft rotates in either a forward or backward direction, so that the vehicle can be moved forwardly or backwardly or can be stopped by braking the engine. When the vehicle turns, the axle shaft at the turning outer side is permitted to freely rotate, while the connection between the propeller shaft and the axle shaft at the turning inner side is retained, so that the turning operation can be effected. Moreover, even when one of the drive wheels encounters slippery conditions such as on a muddy road, the vehicle can continue its travel by the driving force of the remaining drive wheel. Therefore, the clutch mechanism thus far described can perform substantially the same function as a conventional differential locking mechanism.
It is well known that conventional differential locking mechanisms are very complicated in construction and enlarged in size. Such mechanisms comprise a large number of parts including smaller and larger gears which are assembled in a gear box, and a multi-layered friction clutch which operates to prevent most of the engine power from being consumed by a drive wheel trapped on a slippery road surface. Moreover, it is impossible for such mechanisms to provide an entirely satisfactory differential locking effect due to inherent slippage of the multi-layered friction clutch.
The present invention is directed towards the provision of a novel clutch mechanism which very effectively provides the aforesaid special clutch action.